Imaging disturbing method and system

ABSTRACT

A method of interfering against image capturing that does not use infrared light. A visible light that satisfies the condition 1 and condition 2 below is radiated. Condition 1: Because of the human vision characteristics, an optical image for the visible light for the interference is difficult to distinguish from an image being projected onto the screen. Condition 2: Because of the characteristics of a means of image capturing, an optical image for the visible light for the interference is recorded and distinguishable from the image on the screen, when the image on the screen is illegally image captured.

TECHNICAL FIELD

[0001] The present invention relates to a technology for interferingagainst an illegal reproduction of an image from a screen in aprojection system.

BACKGROUND ART

[0002] The U.S. Pat. No. 6,018,374 proposes a technology for interferingagainst such an illegal activity. This technology is based on adifference between the characteristics of human vision and the imagecapturing characteristics of image capturing cameras and uses aninfrared light as a means of interference. Specifically, an infraredradiation apparatus, which is placed at a position close to or far awayfrom an image projector, radiates an infrared light on a screen, so thata reflective light may radiate into an image capturing camera belongingto an individual who is engaged in an illegal activity. In other words,the illegally captured image may record the optical images of theinfrared light that is unrelated to the image being presented. As aresult, the quality may be lost in the image, that has been illegallycaptured, and, in some cases, the illegal activity may be identified. Ofcourse, the infrared light is undetectable to a human, and the viewermay not experience any difficulty viewing the image being presented.

[0003] Such a use of the infrared light may make it possible to realizean adequate interference effect and prevention effect. However, adiverse interference technology needs to be established in order toprotect critical contents.

DISCLOSURE OF THE INVENTION

[0004] The present invention proposes a technology for interferingagainst image capturing using a visible light that satisfies thefollowing conditions:

[0005] Condition 1: Human visual characteristics make it difficult todistinguish between an optical image of the visible light for theinterference and an image projected on a screen.

[0006] Condition 2: Because of the image capturing characteristics of ameans of image capturing, the optical image of the visible light for theinterference may be distinguishable from the image on the screen in arecording, when the image on the screen is illegally captured.

[0007] An effect similar to the case of infrared light may be realizedusing the visual light that satisfies these conditions. In other words,information and images, that are not in the content being presented, maybe viewed in an image that has been illegally captured but may not berecognizable during a normal viewing.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008]FIG. 1 is a diagram showing the characteristics for the humanincrement threshold for contrast sensitivity.

[0009]FIG. 2 is a diagram showing a human optical spectrum sensitivitycurve.

[0010]FIG. 3 is a diagram showing a video camera optical spectrumsensitivity curve.

[0011]FIG. 4 is a diagram showing an example of a configuration of avisible light radiation apparatus (of a type that controls a volume ofoptical emission).

[0012]FIG. 5 is a diagram showing an example of a configuration of avisible light radiation apparatus (of a type that controls a transmittedvolume).

[0013]FIG. 6 is a diagram showing an example of a layout for aprojection apparatus (of a front projection type).

[0014]FIG. 7 is a diagram showing an example of a layout for aprojection apparatus (of a rear projection type).

[0015]FIG. 8 is a diagram showing an example of a layout for a visiblelight radiation apparatus (of a front projection type).

[0016]FIG. 9 is a diagram showing an example of a layout for a visiblelight radiation apparatus (of a rear projection type).

[0017]FIG. 10 is a diagram showing an example of a layout for a visiblelight radiation apparatus (of a peripheral radiation type).

[0018]FIG. 11 is a diagram showing an example of a layout for a visiblelight radiation apparatus (of a back surface output type).

[0019]FIG. 12 is a diagram showing an example of a configuration of asynchronizing apparatus (of a real time type).

[0020]FIG. 13 is a diagram showing an example of a configuration of asynchronizing apparatus (of a storage type).

[0021]FIG. 14 is a diagram showing an example of a configuration of anexperimental system.

[0022]FIG. 15 is a diagram showing an example of a screen configuration.

[0023]FIG. 16 is a diagram showing an example of optical image patterns(1).

[0024]FIG. 17 is a diagram showing an example of optical image patterns(2).

[0025]FIG. 18 is a diagram showing an example of a system based on amethod of projecting a visible light for the interference from a frontside of the screen.

[0026]FIG. 19 is a diagram showing an example of a system based on amethod of projecting a visible light for the interference from a backside of the screen.

[0027]FIG. 20 is a diagram showing an example of a system based on amethod of projecting a visible light for the interference, which isreflected by a means of reflection, from a back side of the screen.

[0028]FIG. 21 is a diagram showing an example of a system based on amethod of radiating a visible light for the interference from the screenperiphery toward the audience.

[0029]FIG. 22 is a diagram showing an example of a system based on amethod of radiating a visible light for the interference during a periodof shuttering.

[0030]FIG. 23 is a diagram showing an example of a configuration of aprojector apparatus using a film.

[0031]FIG. 24 is a diagram showing a relationship between a shutteroperation and a projection operation for a visible light for theinterference.

[0032]FIG. 25 is a diagram showing an example of a shutter sensorlayout.

[0033]FIG. 26 is a diagram showing an example of a system based on amethod of controlling a radiation of a visible light for theinterference based on reproduced data or received data.

[0034]FIG. 27 is a diagram showing an example of a system based on amethod of automatically adjusting a projection position, which is linkedto a change in the screen size.

[0035]FIG. 28 is a diagram showing an example of a way in which thevisible light radiation apparatus and a radiation direction driverapparatus are attached.

BEST MODE OF CARRYING OUT THE INVENTION

[0036] (A) Basic Principle

[0037] (A-1) Conditions Required for Visible Light

[0038] A visible light that satisfies the conditions 1 and 2, which weredescribed earlier, may provide an interference effect mentioned earlier.These conditions were established through research efforts over theyears by the inventors on the human vision characteristics, which havebeen applied on the present field of technology. These conditions aresatisfied by controlling the luminance and chromaticity of the visiblelight for the interference as described next.

[0039] Firstly, chromaticity conditions will be described. For example,when the visible light for the interference and the image beingpresented are radiated so as to overlap together, it is required thatthe chromaticity of the visible light for the interference and thechromaticity of the image being presented match or only be slightly offto a degree that may not affect the human vision. Of course, this is tokeep the visible light for the interference from being detectable by thehuman vision.

[0040] Therefore, when the image being presented is in color, visiblelight of different chromaticities are radiated in accordance withoverlapping positions within a single image. Of course, if the imagebeing presented is a video image, then the chromaticity may be changedin response to changes of the video image even at a same position ofoverlap on the screen. If the image being presented is in black andwhite, then the visible light for the interference does not have to beof varying chromaticity, as long as the chromaticity of the visiblelight for the interference matches with the color temperature on thescreen (image). In other words, the visible light for the interferencemay remain undetectable by the viewer even as the chromaticity remainsconstant.

[0041] When the visible light for the interference is radiated from aspace outside of the screen toward the individual engaged in the illegalactivity, the chromaticity of the visible light for the interferenceshould match the chromaticity of the background where the radiationoriginates. The background chromaticity may be almost constant in mostcases, or the chromaticity may also change gradually. Therefore, avisible light of a predetermined chromaticity may be radiated or thechromaticity of the visible light may be controlled based on actualmeasurement results.

[0042] By the way, a difference in the background for the visible lightfor the interference, i.e. whether the background is a part of the imagebeing presented, is not an essential issue in determining the conditionsthat the visible light for the interference must satisfy. Therefore, thedescriptions below will relate to instances in which the visible lightfor the interference and the image being presented are overlapped,unless specified otherwise.

[0043] Luminance conditions will be described next. The higher is theluminance of the visible light for the interference, the more likelywill the shape of the visible light be recognized by the viewer as anoise on the screen. As a result, the viewer will experience adifficulty in viewing the presentation. Therefore, a luminance of thevisible light for the interference is required to be approximately thesame or less than the viewer's contrast sensitivity increment threshold.

[0044] The contrast sensitivity increment threshold is a value definedas follows, when a visual target is viewed within a background light.When the luminance of the visual target is enhanced with respect to theluminance of the background light, an observer may detect a differencebetween the two, as soon as a difference in luminance is greater than orequal to a certain value. A minimum difference in luminance, at whichsuch a difference is detected, corresponds to the above-mentionedcontrast sensitivity increment threshold.

[0045] Therefore, it is possible to keep the viewer from detecting anincrease in luminance in an area of overlap, as long as the luminance ofthe visible light for the interference is controlled to be atapproximately the same level or a lower level than the incrementthreshold, which is calculated based on the luminance of the image beingpresented, with which the overlap takes place. In other words,information other than the main feature presentation may be superimposedwithout disturbing the audience's viewing.

[0046] Although the contrast sensitivity increment threshold may bemeasured for each viewer, appropriate results may also be obtained ingeneral by taking advantage of research results from the past. Forexample, Section 2, Chapter 3 of a reference material “Light andIllumination” (Hanz Jurgen Henschell, translated by Reo Mori, NipponRikou Shuppankai, Tokyo, 1995) may be used as a reference.

[0047]FIG. 1 shows a relationship between an adaptation luminance(surrounding luminance) L and a luminance ratio sensitivity L/ΔLs in afield vision for testing with a visual angle of greater than or equal toa 1 degree. In this figure, ΔLs is an increment threshold, while L is anadaptation luminance (surrounding luminance). As shown in FIG. 1, therelationship between the adaptation luminance (surrounding luminance)and the luminance contrast sensitivity does not remain constant. Nordoes the increment threshold ΔLs increase without a limit in proportionto the adaptation luminance (surrounding luminance L).

[0048] Furthermore, according to Paragraph 1, Section 1, Chapter 4 ofanother reference, “Bio-information system theory” (Tadahiko Fukuda,Sangyo Tosho, Tokyo, 1995), the increment threshold in general can beeasily calculated using the Stevens Law. According to the Stevens Rule,the increment threshold ΔLs can be expressed by the following equation.

ΔLs=k(L−L′){circumflex over ( )}b  (1)

[0049] where L is an adaptation luminance, L′ is an absolute luminancethreshold, and k and b are constants and are values that change withviewing conditions.

[0050] Information other than the main feature presentation can besuperimposed with the image being presented without being detected bythe majority of viewers by controlling the radiation of the visiblelight for the interference at a luminance that is lower than or equal toa value thus calculated.

[0051] By the way, video camera's sensitivity in distinguishing adifference in the optical intensity is not very different from theincrement threshold of the human eyes. For this reason, the inventorsfocused on a difference between the optical spectrum sensitivity curve(relative luminous efficiency) for the human eyes and the opticalspectrum sensitivity curve (sensitivity to the received light at variouswavelengths) for the video camera, in order to examine additionalconditions.

[0052] The description next will be based on FIG. 2 and FIG. 3. FIG. 2shows the optical spectrum sensitivity curve for the human eyes. FIG. 3shows the optical spectrum sensitivity curve for the video camera.Specifically, FIG. 3 is a characteristic curve for the ICX259AL(manufactured by Sony). A similar type of characteristics curve has beenpresented in Section 3, Chapter 2 in a reference, “Light Detector andMethod of Use” (Ryo Takamura, Norihito Suzuki, editor, Gakkai ShuppanCenter, Tokyo, 1991).

[0053] As shown in FIG. 2, the optical spectrum sensitivity curve forthe humans shows a maximum value at around 555 nm and shows reducedsensitivity at short wavelengths and long wavelengths in a bright fieldcondition. Sensitivity is maximum at around 525 nm in a dark fieldcondition. On the other hand, the optical spectrum sensitivity curve forthe video camera in FIG. 3 does not completely match with the opticalspectrum sensitivity curve for humans, although they are made similar toeach other through an optical correction, using a color filter, and anelectronic correction. This is because the sensitivity to the incominglight in an image capturing device (CCD: charge coupled device), whichis used in the video camera, goes down more gradually compared with thehuman at the lower wavelengths and higher wavelengths.

[0054] In fact, while the human optical spectrum sensitivity is atalmost 0 at 400 nm on a side of short wavelength or 700 nm at a side oflong wavelength, the video camera's optical spectrum sensitivity is 0.6at 400 nm on a side of the short wavelength and 0.7 at 700 nm on a sideof the long wavelength, according to FIG. 2 and FIG. 3. Therefore, whenthe maximum value for the human optical spectrum sensitivity and themaximum value for the video camera optical sensitivity are approximatelythe same, the video camera's sensitivity for received light is ingeneral be higher than the human's sensitivity for received light at along wavelength and at a short wavelength. In other words, when avisible light of these wavelengths is used, an optical image forinterference may be recorded distinguishably from the image beingpresented in an image that has been captured using an image capturingmeans, such as a video camera.

[0055] Accordingly, effects described next may be realized as a resultof a radiation of a visible light for the interference that satisfiesthe conditions listed above. Firstly, the chromaticity of the visiblelight is similar to the image being presented, and the luminance is lessthan or equal to the contrast sensitivity increment threshold. As aresult, the viewer cannot distinguish between the two. Even when thevisible light for the interference is projected on a specific spot onthe screen on which the image being presented is projected, the image atthis projection spot may seem uniform, and an existence of the visiblelight for the interference may not be detected.

[0056] On the other hand, the video camera can record the light andshade of the contrast in the object being image captured, that may notbe detectable to the human because of the differences in the opticalspectrum sensitivities. Therefore, by radiating the visible light forthe interference that satisfies the conditions listed above so as tooverlap with the image being presented, it is possible to make theoptical image of the visible light for the interference show up and bedistinguishable in the captured image, when the image being presented isillegally captured. For example, a desirable marking that is unrelatedto the image being presented may be recorded on the screen, if anoptical image of an arbitrary shape were used as the visible light forthe interference.

[0057] (A-2) Generating Optical System for the Visible Light

[0058] A generating optical system for the visible light that satisfiesthe conditions listed above will be described. As mentioned earlier, thechromaticity of the visible light for the interference is required tomatch the background chromaticity in the direction from which the lightis emitted. The background chromaticity may correspond with thechromaticity of the image that is projected on the screen, as mentionedearlier, or may correspond with the chromaticity of the light arrivingfrom an object that exists outside of the screen. In either of thesecases, it is necessary to generate a visible light with a arbitraryluminance and chromaticity.

[0059] Such a visible light can be generated by a visible lightradiation apparatus having a configuration described next. For example,as shown in FIG. 4 and FIG. 5, a plurality of single color lights may bemixed for generating a visible light with an arbitrary luminance andchromaticity. The chromaticity can be expressed in relation to the XYplane coordinate, and the chromaticity of the visible light, resultingfrom color mixing, is a weighted average of each of the single coloredlights, the weight of which is determined by the luminance. Therefore,by controlling the luminance of each of the single colored lights in thecolor mixture, a visible light of an arbitrary luminance andchromaticity may be generated on a line of spectrum that connects twopoints in the chromaticity coordinate, which correspond with the singlecolored lights in the mixture (two colors), or within an area bound bylines that connect points in the chromaticity coordinate, whichcorrespond with the single colored lights in the mixture (three or morecolors).

[0060]FIG. 4 shows an example of a configuration of a visible lightradiation apparatus based on a method of controlling individually thevolumes of light from three types of single colored light sourcescorresponding to a red color, a green color, and a blue color. In thisfigure, 1R refers to a single colored light source apparatus that emitsa red colored light, 1G refers to a single colored light sourceapparatus that emits a green colored light, and 1B refers to a singlecolored light source apparatus that emits a blue light. Optical volumecontrol signals SR1, SG1, and SB1, which are used for controlling theemission volume, are fed to each single colored light source apparatus,respectively. A light emitting diode (LED) or a laser (not limited to asolid state laser) may be used for the single colored light sourceapparatuses. 2 in the figure refers to a mixer optical system. As themixer optical system 2, a dichroic mirror, a dichroic prism, anintegrating sphere, or their combinations may be used.

[0061] In the figure, 3 refers to a projection optical system. Theprojection optical system 3 consists of projection lenses and otheroptical devices.

[0062]FIG. 5 shows an example of a configuration of a visible lightradiation apparatus based on a method of controlling a volume ofreflected or transmitted light and includes optical volume adjustableapparatuses in optical paths for the three types of single colored lightsources, which correspond with the red light, the green light, and theblue light. In the figure, 1R, 1G, and 1B refer to single-light sourceapparatuses that emit the red light, the green light, and the bluelight, respectively. In the system in FIG. 5, the volume of the singlecolored light emitted by each of the single colored light sourceapparatuses is fixed.

[0063] The optical volume adjustable apparatuses 4R, 4G and 4B, whichare placed in the optical paths for the various single colored lights,which come into the mixer optical system 2, is characteristic of FIG. 5.Liquid crystal devices or neutral density filters (ND filters) may beused for the optical volume adjustable apparatus. When the liquidcrystal device is used, the transmitted volume of light can beconstantly adjusted with the optical volume control signals SR2, SG2,and SB2. When the neutral density filter is used, the rate ofattenuation remains fixed for each device. In addition, as the volume oflight in the optical volume adjustable apparatus, a means that controlsthe optical volume by mechanically adjusting an aperture size or a meansthat controls the optical volume by adjusting a time over which ashutter is kept open may be used.

[0064] While the three types of single colored light sources are set upindependently in FIG. 4 and FIG. 5, they may also be stored within asingle package. In other words, a full color optical source may be used.By the way, the visible lights radiating from the single colored lightsources only need to be perceived by the viewer as a color mixture.Therefore, the configuration of the visible light radiation apparatusdoes not necessarily need to include the various optical systemsmentioned above (dichroic mirror, dichroic prism, integration sphere,projection optical system).

[0065] (A-3) An Example of a Layout of the Visible Light RadiationApparatus

[0066] A layout that may be used for the visible light radiationapparatus will be described next. An example of the layout that will bedescribed next may be used for both an image projected from a front sideof the screen, as shown in FIG. 6, and an image projected from behind asemi-transparent screen, as shown in FIG. 7.

[0067] The method of placing the projection apparatus 5 in front of thescreen 6, as shown in FIG. 6, for viewing a reflected optical image willbe called a front projection method. The method of placing theprojection apparatus 5 behind the semi-transparent screen 8, as shown inFIG. 7, for viewing the transmitted optical image will be called a rearprojection method. By the way, a reference numeral 7 represents areflective mirror that bends an optical path of a beam of lightradiating from the projection apparatus 5 in FIG. 7.

[0068] Coming back to the description of the visible light radiationapparatus, the visible light radiation apparatus may be placed at thefollowing locations. For example, as shown in FIG. 8, the visible lightradiation apparatus 10 may be placed in front of the screen 9, in orderto interfere against the illegal activity using a reflected light, thatradiates toward the audience.

[0069] As shown in FIG. 9, the visible light radiation apparatus 10 mayalso be placed behind the screen 9 in order to interfere against theillegal activity using an optical beam, that transmits through or passesthrough the screen. If the light, that transmits through the screen,were to be used, the chromaticity of the transmitted light is requiredto match the chromaticity of the image being presented, as detected bythe viewer.

[0070] Or, as shown in FIG. 10, the visible light radiation apparatus 10may be placed at the peripheral of the screen 9, in order to radiate thevisible light for the interference directly into the image capturingapparatus used by the perpetrator of the illegal activity. Although aplurality of the visible light radiation apparatus units is shown inFIG. 10, it is also possible to only use one unit at one of thelocations. In this layout example, however, the position of the visiblelight radiation apparatus is not limited to the screen periphery and,instead, can be behind the screen or in front of the screen. In essence,the layout example in FIG. 10 represents the visible light, that is usedfor the interference, being projected toward the viewer through a spaceoutside of the screen. The viewer sees the incoming visible light forthe interference directly.

[0071] Or, as shown in FIG. 11, the visible light radiation apparatus 10may be placed on the back side of the screen 9, in order to use theoptical beam, that passes through or transmits through the screen, inorder to interfere against the illegal activity. When the lighttransmitting through the screen is used, the chromaticity of thetransmitted light is required to match the chromaticity of the imagebeing presented as detected by the viewer. The visible light radiationapparatus may be placed over the screen or near the screen. In FIG. 11,the visible light radiation apparatus is placed above the screen. By theway, a part of or the entire visible light radiation apparatus may beembedded inside the screen. In such an instance, an aperture, from whichthe visible light radiates, may be exposed at the surface of the screenor be embedded inside a screen.

[0072] Although a single unit of the visible light radiation apparatusis shown in each of FIG. 8 and FIG. 9, a plurality of the visible lightradiation apparatus units may also be placed in all of these cases.While the visible light radiation apparatus shown in these figuresbasically radiates light in only one direction, the direction ofradiation may be made variable in order to radiate the visible light ina plurality of directions.

[0073] (A-4) Method of Synchronizing the Luminance and Chromaticity Withthe Image Being Presented

[0074] A method of synchronizing the visible light, that is used for theinterference, with the image being presented will be described next. Inother words, a method of variably controlling the luminance andchromaticity of the visible light used for the interference, in responseto the image being presented, will be described. If the visible lightfor the interference passes through a space outside of the screen, thenthe method may be used in a system for synchronizing the chromaticityand luminance of the visible light, which is used for the interference,with a background light.

[0075] The image being presented and the visible light radiationapparatus may be synchronized, for example, using the following methods.The visible light radiation apparatus may be controlled based oninformation calculated in real time. Or, the visible light radiationapparatus may be controlled using information calculated in advance. Theformer method is used for projecting the image being presented using adigital type projection apparatus. The latter method is used forprojecting the image being presented using a film based projectionapparatus. FIG. 12 and FIG. 13 show examples of the systemscorresponding to each method.

[0076] (1) First System Example

[0077]FIG. 12 shows an example of a configuration of a synchronizingapparatus 11 when a digital type projection apparatus is used. Thesynchronizing apparatus 11 includes an image data memory 12, an imagedata read-out unit 13, a radiation data calculation unit 14, a radiationdata memory 15, and a radiation data read-out unit 16.

[0078] The image data memory 12 records the image data for the mainfeature program presentation. The image data memory 12, however, doesnot need to store the entire image data for the entire screen and may,instead, the store image data related to positions at which the visiblelight for the interference will be superimposed. The image data read-outunit 13 reads out a frame number for the image data or a comparable datanumber from the image data memory 12. By the way, the image dataread-out unit 13 needs to read out the image data only when the visiblelight for the interference is radiating. For example, the reading maytake place once every few frames or when the scene changes. The unit ofreading may be a single frame or a plurality of frames.

[0079] The radiation data calculation unit 14 calculates thechromaticity and luminance of the image data for each frame number (andfor each position of superimposition, when the visible light for theinterference is superimposed at a plurality of locations within a singleframe). In general, the image data for the presentation consists ofprimary color data for red, green, and blue. Therefore, the radiationdata calculation unit 14 uses directly the chromaticity data, in theimage data for the presentation, for the chromaticity data for thevisible light for the interference. On the other hand, the luminancedata needs to be below the human contrast sensitivity incrementthreshold. The radiation data calculation unit 14 calculates theappropriate luminance values using, for example, the equation (1)described earlier. These calculation processes take place before theapplicable image is projected onto the screen.

[0080] The radiation data memory 15 temporarily stores the radiationdata calculated by the radiation data calculation unit 14. In otherwords, the radiation data memory 15 functions as a buffer for storingthe calculated radiation data until the radiation data is read out.

[0081] The radiation data read-out unit 16 reads the radiation data,which corresponds with the frame number, or a data number, that isassigned to the image being presented that is to be projected, from theradiation data memory 15. The frame number or the corresponding datanumber, that is assigned to the image being presented, is provided bythe projection apparatus that projects the image being presented.

[0082] While the description here is based on the visible lightradiation apparatus, which radiates the visible light for theinterference, being a separate unit from the projection apparatus, thatprojects the image being presented, the two units may also make up asingle unit.

[0083] By the way, the luminance of the image being presented may beadjusted down by an amount calculated for the luminance of the visiblelight for the interference, in this instance. In the case of a singleunit, an optical system and other parts are used for both theinterference optical system and the image presentation optical system,and a misalignment and a chromaticity mismatch, which may be caused bydifferences in optical characteristics, may no longer be an issue. Ofcourse, optical systems having equivalent characteristics may be usedfor the interference optical system and for the presentation opticalsystem, when the two apparatuses are separately provided.

[0084] (2) Second System Example

[0085] A system example in FIG. 13 will be described next. FIG. 13 showsan example of configuration for a synchronizing apparatus 17, which isused for a film based projection apparatus. The synchronizing apparatus17 includes a preprocessing unit 17A and a real time processing unit17B. The preprocessing unit 17A corresponds with the image data memory12 through the radiation data memory 15 in FIG. 12. In other words, thepreprocessing unit 17A includes an image data memory 18, an image dataread-out unit 19, a radiation data calculation unit 20, and a radiationdata memory 21.

[0086] The image data memory 18 stores data collected in advance using,for example, a spectrum radiance luminance meter on the image beingpresented, which is projected onto the screen during, for example, atest screening. Of course, the image data memory 18 does not need tostore the image data for the entire screen and, instead, may store onlythe image data corresponding with the positions at which the visiblelight for the interference is to be superimposed. The image dataread-out unit 19 reads out a frame number for the image data, or acorresponding data number, from the image data memory 18. The image dataread-out unit 19 needs to read out the image data only when the visiblelight for the interference is to be radiated. For example, the readoutmay take place once every few frames or when the scene changes. The unitof readout may be a single frame or a plurality of frames.

[0087] The radiation data calculation unit 20 calculates thechromaticity and luminance of the image data for each frame number (orfor each position of superimposition, when the visible light for theinterference is to be superimposed at a plurality of locations in asingle frame). In general, the image data for the presentation consistsof primary color data of red, green and blue. Therefore, the radiationdata calculation unit 20 uses the chromaticity data for the image beingpresented directly for the chromaticity data for the visible light forthe interference. On the other hand, the luminance data is required tobe equal or less than the human contrast sensitivity incrementthreshold. The radiation data calculation unit 20 calculates theapplicable luminance values using, for example, the equation (1)described earlier. The calculation process takes place before thecorresponding image is projected onto the screen.

[0088] The radiation data memory 21 temporarily stores the radiationdata calculated by the radiation data calculation unit 20. In otherwords, the radiation data memory 21 functions as a memory apparatus forstoring the calculated radiation data until a time the image isprojected on the screen. The memory apparatus may be based on a magneticrecording medium, an optical recording medium, an opto-magneticrecording medium, or a semiconductor memory.

[0089] By the way, the processing contents of the preprocessing unit maybe executed by a server apparatus which is connected by a network, anddownloaded before or during the projection of the image being presented.In such an instance, a communications apparatus for downloading and amemory apparatus for storing data that has been downloaded are requiredat each projection position, which functions as a client.

[0090] The real time processing unit 17B includes a radiation datamemory 21 and a radiation data read-out unit 22. The radiation dataread-out unit 22 reads the radiation data, corresponding to the framenumber assigned to the image in the presentation, that is to beprojected, or the corresponding data number from the radiation datamemory 21. By the way, the frame number assigned to the image beingpresented or the corresponding data number is provided by the projectionapparatus that projects the image being presented.

[0091] (A-5) Experimental Results

[0092] An example of a assumed system for the embodiment will bedescribed first. When the image being presented is projected using aprojector, a white color light source, such as a halogen lamp or a metalhydride lamp, will be used as an optical source. The image beingpresented is shown on a screen, as a beam of light radiates from thesource of white color light, passes through a color filter, and isprojected using an optical system. In the present invention, the visiblelight, that satisfies the conditions described earlier, is projectedonto specific areas of the image being projected. In other words, thevisible light, having the same chromaticity as the image being presentedand a luminance level that is approximately the same or below the humancontrast sensitivity increment threshold, which is obtained based on theimage being presented, is projected onto the screen.

[0093] Assuming such an embodiment, the inventors of the presentinvention have verified an effectiveness of the present invention usingan experimental system shown in FIG. 14. A halogen light source 23,which is connected to a surface emission light guide 24, is used as asource of white color light in this experimental system. The halogenlight source 23 being used is manufactured by Mejiro Precision andconsumes 100W of electrical power. The surface emission light guide 24is the MPP90-1500S, which is manufactured by Moritechs, and has a 90 mmsquare emission surface.

[0094] On the other hand, the visible light radiation apparatus, thatradiates the visible light for the interference, includes an integrationsphere 25, which includes three types of single colored light sourcesand is driven by an arbitrary waveform generator 26. A red color LED isthe HLMPD 105, which is manufactured by Hewlett Packard. A green colorLED is the NSPG 500S, which is manufactured by Nichia Chemical. A bluecolor LED is the NSPB 500S, which is manufactured by Nichia Chemical.The arbitrary waveform generator 26 is the AWG 2005, which ismanufactured by Sony Tectronix.

[0095] As a composition means 27 for the visible light, which is emittedby the two parts, a plate beam splitter (half mirror) is used. Anapparatus mentioned below is placed in an area 28 as an apparatus forverifying how the visible light, after the composition, is imagecaptured. A luminance meter (BM-5A, manufactured by Topcon) is placedfor measuring the chromaticity and luminance. The CCD-MC100, which ismanufactured by Sony, is used as a video camera for image capturing. TheGV-D900, which is manufactured by Sony, is used as a video deck thatincludes a display unit for verifying the images being recorded.

[0096] Measurement results were as follows. Firstly, a measurement wastaken only for the visible light radiating from the surface emissionlight guide, and the result for the xy chromaticity was (x, y, L(luminance, cdm {circumflex over ( )}−2))=(0.448, 0.419, 40.2), whichmay correspond with an image that was projected using the white colorlight source.

[0097] Next, a visible light, which is 10 mm square in size andradiating from the integration sphere, is superimposed on the image, andmeasurements were taken at the area of overlap. The volume of light fromthe integration sphere is adjusted, so that the measurement taken at thearea of overlap may be (x, y, L)=(0.448, 0.419, 41.0). In other words,the chromaticity in the area of overlap with the visible light from thesurface emission light guide is made to match the area with only thevisible light from the surface emission light guide, while the luminanceis increased only by the increment threshold, by adjusting the volume oflight from the integration sphere.

[0098] An observer observing the result was not able to distinguishbetween the area, with only the visible light from the surface emissionlight guide, and the area of overlap, with the visible light from theintegration sphere and this visible light. On the other hand, an image,that has been captured using a video camera and shown on a display,showed a contrast difference between the two. In other words, it wasverified that a person may not be able to make a distinction, but thevisible light for the interference may be recorded in the image capturedillegally using the video camera.

[0099] (B) Conceptual Embodiment

[0100] Next, a conceptual embodiment that will be applicable to thevarious embodiments based on the visible light, that satisfies theCondition 1 and the Condition 2, will be described.

[0101] (1) A method is proposed for interfering against illegalactivities by radiating a visible light for the interference from aviewer's side toward a screen and using a reflected light from thescreen surface. In this instance, the visible light for the interferenceis projected from the front of the screen toward the screen. Thisembodiment corresponds with FIG. 8. The visible light radiationapparatus does not need to directly face the screen, as long as theposition is in front of the screen. For example, the visible lightradiation apparatus may be placed in front of the screen at an angle. Insuch an instance, the visible light radiation apparatus may be placednear the periphery of the screen, so that the visible light may beradiated almost in parallel with the screen. Of course, the distancebetween the screen and the visible light radiation apparatus may besmall or large. Furthermore, a means of reflection (for example, amirror) may be installed for projecting the visible light, reflectingoff the means of reflection, as the visible light for the interferenceonto the screen.

[0102] By the way, the projection apparatus, that projects the imagebeing presented, may be placed in front of the screen, as shown in FIG.6, or may be placed in a position behind the screen, as shown in FIG. 7.

[0103] (2) A method is proposed in which a visible light for theinterference is radiated from behind the screen onto the screen, and alight transmitting through the screen and reaching the viewer is usedfor interfering against an illegal activity. In other words, the visiblelight for the interference, which is projected from behind the screentoward the screen surface, transmits through the screen toward the frontside of the screen in the proposed method. This scheme corresponds withFIG. 9. As long as the visible light radiation apparatus is in the backside of the screen, the apparatus may be positioned in such a way as tonot directly face the screen. For example, the visible light radiationapparatus may be placed at an angle in front of the screen. Or, a meansof reflection (for example, a mirror) may be set up, and the visiblelight reflecting off this means of reflection may be used as a light forthe interference and projected onto the screen.

[0104] By the way, the following transmission paths are possible for thevisible light for the interference, based on the structure of thescreen. For example, when a part of the screen is thinner than otherareas on the screen (for example, the screen has a concave shape), thenthe transmission may take place in this particular area. Or, if amaterial that may easily allow the visible light to transmit through isembedded into a part of the screen in order to allow the visible lightfor the interference to transmit through, then the visible light maytransmit through this material. If the entire screen is made of amaterial that may easily allow the visible light to transmit through,then the visible light may transmit through any part of the screen.

[0105] In these instances, the projection apparatus, that projects theimage being presented, may be placed in front of the screen, as shown inFIG. 6, or behind the screen, as shown in FIG. 7.

[0106] (3) A method is proposed, in which a visible light for theinterference is radiated onto a screen from behind the screen, and apassing light, that passes through an part for passing in the screen, isemitted toward the viewer in order to interfere against an illegalactivity. In other words, the visible light for the interference isprojected from a position behind the screen toward the screen surfaceand passes through the screen and travels toward the front of the screenin the method being proposed. This scheme corresponds with FIG. 9.Except that the visible light for the interference passes through thescreen, the scheme is similar to the one described in (2).

[0107] This part for passing may be a break or a gap (for example, aslit), that extends in one direction; a hole portion that penetratesthrough the screen (for example, a small hole or a hole); or otherstructures that may allow the visible light to pass through from theback side to the front side of the screen. There should be at least onepassing part created on the screen. If there is a plurality of passingparts, then the location for passing may be made selectively variable.Furthermore, the passing part may be laid out across the entire screenor may be concentrated at a specific area (for example, at the center ofthe screen or at the periphery of the screen). An example is shown inFIG. 15. FIG. 15 shows the passing parts 30, that are laid out across anentire surface of a screen 29.

[0108] (4) A method is proposed in which a visible light for theinterference is reflected off a means of reflection, and a reflectedlight is radiated onto the screen. As explained in (2) and (3), thevisible light for the interference, that is projected onto the screen,is not limited to those directly projected from a visible lightradiation apparatus. When a means of reflection, such as a mirror isused instead, a higher degree of freedom is allowed with the positionfor installing the visible light radiation apparatus.

[0109] The means of reflection or its reflection surface may be capableof arbitrary changing the direction of reflection by a means of driving.Even when the visible light for the interference is projected to aplurality of areas, the visible light radiation apparatus may not needto be installed for all of such areas, when the means of driving isutilized. In other words, an interference over a wider range is madepossible. Furthermore, the means of driving may be used as a means ofadjustment for precisely targeting the position of the visible light forthe interference on to a target pixel.

[0110] By the way, the present embodiment may be used for both thevisible light for the interference radiating from the front of thescreen or for the visible light for the interference radiating frombehind the screen. Of course, the position of the projection apparatus,which projects the image being presented onto the screen, may not belimited to any particular position.

[0111] (5) A method is proposed in which visible lights for theinterference in prescribed combinations are radiated onto a plurality ofspots on a screen, so that a two dimensional optical image pattern maybe simultaneously recorded with an image on a screen that is illegallycaptured. In the present embodiment, optical images, such as those shownin FIG. 16 or FIG. 17, may appear in the recorded image display, whenthe image is captured illegally. FIG. 16 shows an optical image patternconsisting of two pieces of optical points 32 on a recorded imagedisplay 31, while FIG. 17 shows an optical image pattern consisting ofthree pieces of optical points 32 on the recorded image display 31.

[0112] With this method, desirable information may be displayed based onthe positions of the optical points and the number of optical pointsdisplayed simultaneously. For example, the desirable information mayinclude an output time and date, an output location, a screen number (aunique number that identifies the screen), an output apparatus number (aunique number that identifies the output apparatus), and otherinformation required for identifying a party involved in the output, aswell as a location of the illegal activity. Any piece of information ora plurality of pieces of information may be represented using binaryoptical point image patterns.

[0113] If the shapes of the point image were variable, then even moreinformation could be displayed. Instead of assigning meanings to therecorded positions of the optical points or the number of optical imagesdisplayed simultaneously, a meaning may also be assigned to a twodimensional shape (a geometric shape, a symbol, and other recognizablepatterns), that is presented by the entire point image.

[0114] The optical image pattern may remain the same throughout thescreening of the image being presented or may be changed periodically orirregularly. Furthermore, the optical image pattern may be projectedthroughout the entire screening of the presentation or may be projectedintermittently.

[0115] Of course, the visible light radiation apparatus may be placed infront of the screen or behind the screen in the present embodiment.Furthermore, the projection apparatus for projecting the image beingpresented may be placed in front of the screen or behind the screen. Thevisible light for the interference, which is radiated onto the screen,may be reflected off a means of reflection.

[0116] If an objective is to make it difficult to view the capturedimage, then the visible light for the interference should be radiated insuch a way that a large number of optical images may be recorded. Or,the projection positions (lighting positions) of the visible light maybe changed in a desired manner.

[0117] (6) A method is proposed in which, when an image being presentedis projected onto a screen by a means of film based projection, a whitecolor light for the interference, a luminance of a target image pixel ofwhich is determined based on an average luminance between a precedingshot and an ensuing shot, is radiated onto the target image pixel on thescreen during a time period in which the projected light is shuttered bya frame forwarding shutter. This method is used particularly for blackand white images, which are projected using a film based projectorapparatus. The present method is characterized in that an emissionperiod for the white color light (the visible light) for theinterference is limited to periods in which the frame forwarding shutteris closed.

[0118] By the way, the length of time during which the frame forwardingshutter shutters the projection light may be detected or predicted basedon a frame forwarding operation or directly detected or predicted basedon the operation of the frame forwarding shutter.

[0119] Of course, no additional restrictions are imposed other than therequirement on the timing of projection for the white color light forthe interference. The white color light for the interference may beprojected from the front side of the screen or projected from the backside of the screen. Furthermore, the image being presented may beprojected from the front side of the screen or projected from the backside of the screen. By the way, the white color light for theinterference only needs to be radiated during some of the time periodsin which the frame forwarding shutter is closed and not during all ofthe time periods. Furthermore, the white color light for theinterference may be radiated during the time periods in which the imagebeing presented is shown in a way similar to the other examples.

[0120] (7) A method is proposed in which a visible light for theinterference, a luminance and chromaticity of a target image pixel ofwhich is determined based on an average luminance and an averagechromaticity between a preceding frame and an ensuing frame, is radiatedon the target image pixel during a time in which a frame forwardingshutter shutters a projection light, when an image being presented isprojected onto a screen using a film based means of projection. Thismethod is used in particular for the images being presented that are incolors. Other aspects are similar to the method in (6).

[0121] (8) A method is proposed in which a direction of radiation of theabove-mentioned visible light for the interference is adjustedautomatically, when a screen size (or aspect ratio) is changed. When thescreen size is changed, the image pixel, onto which the visible lightfor the interference should be projected, moves physically.Consequently, the position from which the visible light for theinterference is projected is required to be adjusted. However, thisprocess is extremely burdensome to execute manually. On the other hand,an operator may only need to take into account the screen size, whenperforming the task, if an automatic adjustment feature were loaded.Efficiency may be significantly improved.

[0122] (9) A method is proposed in which a visible light for theinterference passes through a space outside of a screen and is directlyradiated on the viewer. In this instance, the visible light for theinterference is reflected off or radiated from an object other than thescreen and is superimposed with a background light. It goes withoutsaying that, even in such an instance, the visible light for theinterference may remain undetectable to a human, as long as thechromaticity and the luminance satisfy the condition 1 and the condition2, which were described earlier, with respect to the background light.

[0123] (10) A method is proposed in which a visible light for theinterference is radiated from an optical source behind a screen surfaceand transmits through the screen to the audience. This method representsa special form of the method described in (2). In other words, thevisible light for the interference is radiated from a position that isclose to the screen back side or adjacent to the screen back side. Thepoint of emission for the visible light for the interference may beadjacent to the screen back side or may face the screen with a small gapin between.

[0124] The path of transmittance may be similar to the example describedin (2). This method may be applied on the image presented with aprojection from the front of the screen or with a projection from theback of the screen.

[0125] (11) A method is proposed in which a visible light for theinterference is emitted from an optical source on a back side of thescreen and passes through a passing part in the screen and reaches theviewer directly. This method is a special form of the method describedin (3). In other words, the visible light for the interference isemitted from a position that is close to the back side of the screen. Inthis instance also, the point of emission of the visible light for theinterference may be adjacent to the screen back side or may face thescreen backside with a small gap in between.

[0126] The screen used in this instance is similar to the one describedin (3). This method may be applied for the image being presented that isprojected from the front of the screen or from the back of the screen.

[0127] (12) A method is proposed in which a visible light for theinterference is emitted out of an optical source, that is embedded in ascreen, and emitted directly to the audience from the screen surface.The embedded optical source may be detachable from the screen or maycomprise a single unit with the screen. The point of emission in theembedded optical source may be buried within the screen or may beexposed at the surface of the screen. By the way, when the point ofemission in the optical source is buried within the screen, the visiblelight for the interference is emitted from the screen surface afterpassing through or transmitting through a part of the screen. By theway, the image being presented may be projected from the front of thescreen or projected from the back of the screen.

[0128] (13) A method is proposed in which visible lights for theinterference are emitted from a plurality of spots on a screen in aprescribed combination in order to have a two dimensional optical imagepattern be recorded, when the image on the screen is illegally captured.This method corresponds with the method described in (5). In the methodin (5), the visible light for the interference was radiated onto thescreen. The present method differs in that the visible lights for theinterference are radiated out of a plurality of points on a screen.

[0129] (14) A method is proposed in which a white color light for theinterference, based on an average luminance between a preceding frameand an ensuing frame at target pixels, are radiated from the targetpixels on a screen, during a time period in which a frame forwardingshutter shuts out a projection light in a film based projection means,which projects an image being presented onto the screen. This methodcorresponds to (6). While the method in (6) was based on a projection ofthe white color light for the interference onto the screen, the presentmethod is based on the white color light for the interference radiatingfrom the screen.

[0130] (15) A method is proposed in which a visible light for theinterference, based on an average chromaticity and an average luminanceof a preceding frame and an ensuing frame at target pixels, is radiatedfrom the target pixels on a screen, during a time period in which aframe forwarding shutter shuts out a projection light in a film basedprojection means for projecting onto a screen an image being presented.This method corresponds with (7). While the method in (7) was based on avisible light for the interference being projected onto the screen, thepresent method differs in that the visible light for the interference isradiated from the screen.

[0131] (16) A method is proposed in which an illegal activity isinterfered with by radiating a visible light for the interference fromthe front of a screen in a system for interfering against imagecapturing and by using a reflected light off of the screen surface. Thepresent system represents an application example for the methoddescribed in (1). Therefore, the descriptions in (1) are applicable onthe present system. Of course, the visible light radiation apparatusdescribed in (A-2) is used. Furthermore, as described in (A-4), thevisible light for the interference and the image being presented aresynchronized, just as in other systems that will be described later.

[0132] (17) A system for interfering against image capturing isproposed, which interferes against an illegal activity by radiating avisible light for the interference from behind the screen and by using atransmitted light, that transmits through the screen toward the viewer.The present system represents an application example for the methoddescribed in (2). Several forms of transmittance are possible based onthe structure and material of the screen.

[0133] (18) A system for interfering against image capturing isproposed, which radiates a visible light for the interference frombehind the screen and uses a passing light, that passes through thepassing part of the screen toward the viewer, in order to interfereagainst an illegal activity. This system represents an applicationexample for the method described in (3). Several forms of passing parts,with various shapes and structures, are possible.

[0134] (19) A system for interfering against image capturing isproposed, which relies on a means of reflection in order to reflect avisible light for the interference and to radiate a reflected light on ascreen. The present system represents an application example for themethod described in (4). The means of reflection itself or the imagecapturing interference system may provide a means of drive for areflection surface, in order to adjust the reflection in any direction.When the direction of reflection is variable, it is possible toprecisely position the point of projection and to project the visiblelight for the interference toward a plurality of areas using a smallnumber of visible light radiation apparatuses.

[0135] (20) A system for interfering against image capturing, whichincludes a plurality of units of the visible light radiation means, isproposed. The visible light radiation means includes a means of controlfor projecting the visible lights for the interference in prescribedcombinations onto a plurality of areas on a screen, so that, when animage on the screen is illegally captured, a two dimensional opticalimage pattern may be recorded simultaneously. The present systemrepresents an application example for the method described in (5).

[0136] The control apparatus may be a, for example, a computer, anapplication specific semiconductor device, or other electronic circuits.The control apparatus may be realized by hardware or software. A meansof switching may also be used, when the two dimensional optical imagepatterns are switched periodically or are projected intermittently. Forexample, a means of switching may be utilized, in which the emission oflight is switch controlled in response to a clock or its frequencydivided output. Furthermore, another means of switching may be utilized,in which the emission is switch controlled in response to a charging anda discharging of a capacitor. In yet another example, a mechanical meansof switching may be used.

[0137] When some form of information is to be encoded into the opticalimage pattern, a means of table may be provided that establishescorrelation relationships between the optical image patterns and theinformation. The radiation of the visible light radiation means may becontrolled, based on the information contained in the means of table,when the visible light for the interference is radiated.

[0138] (21) A system for interfering against image capturing is proposedfor an image being presented on a screen by a projection method using afilm based means of projection. The image capturing interference systemincludes a visible light radiation means for radiating a white colorlight for the interference onto the screen; a shutter cycle detectionmeans for detecting the time periods during which a frame forwardingshutter shutters the projected light; a means of calculation fordetermining a luminance of the white color light for the interferencebased on an average luminance in a previous frame and an ensuing framein the target image pixels; and a means of control for projecting thewhite color light for the interference onto the target image pixelsduring the time period in which the projection light is shuttered. Thepresent system represents an application example for the methoddescribed in (6). In other words, the present system is suited for ablack and white image being projected using a film based means ofprojection.

[0139] The shutter cycle detection means may be a method of mechanicallydetecting the frame forwarding; a method of electronically detecting theframe forwarding based on, for example, a change in an electrostaticcapacitance; a method of mechanical detection based on an operation of ashutter mechanism; a method of electronic detection based on theoperation of the shutter mechanism; or a method of optical detectionbased on the operation of the shutter mechanism.

[0140] The means of calculation calculates an average luminance for theprevious frame and the ensuing frame and factors in the human contrastsensitivity increment threshold, in order to determine the luminance ofthe white color light for the interference that is to be radiated. Thecontrol means controls the periods of emission based on the detectionresults from the shutter cycle detection means. A computer, anapplication specific semiconductor device, or other electronic circuitsmay, for example, be used as the means of calculation or as the means ofcontrol. This means may be realized by hardware or by software.

[0141] (22) A system for interfering against image capturing is proposedfor an image being presented on a screen by a projection method using afilm based means of projection. The image capturing interference systemincludes a visible light radiation means for radiating a visible lightfor the interference onto the screen; a shutter cycle detection meansfor detecting the time periods during which a frame forwarding shuttershutters the projection light; a means of calculation for determining aluminance and chromaticity of the visible light for the interferencebased on an average luminance and average chromaticity in a previousframe and an ensuing frame in the target image pixels; and a means ofcontrol for projecting the visible light for the interference onto thetarget image pixels during the time period in which the projection lightis shuttered. The present system represents an application example forthe method described in (7). The various means described in (21) areused in the present system. Of course, the means of calculation requiresa different structure for calculating the average luminance and theaverage chromaticity.

[0142] (23) A system for interfering against image capturing isproposed, that includes a means of radiating a visible light for theinterference on to a screen, a means of driving the radiation directionfor driving the means of radiating the visible light and changing thedirection of radiation; a means of storage for storing information onthe directions of radiation for the means of radiating the visible lightin response to a screen size; and a means of radiation direction controlfor reading out the appropriate information on the direction ofradiation from the means of storage and providing the information to themeans of driving the radiation direction, when an instruction forchanging the screen size is detected, and for automatically adjustingthe directions of radiation of the visible light for the interference,which is emitted from the means of radiating the visible light. Thepresent system represents an application example for the methoddescribed in (8).

[0143] The screen size (or the aspect ratio) may be standard (1:1.33),Europe Vista (1:1.66), America Vista (1:1.85), scope (1:2.35), orothers. The numeric values mentioned are examples of representativevalues and are not limited to these values.

[0144] The means of driving the radiation direction may include, forexample, a means of turning the means of visible light radiation aroundan attachment axis; a means of rotating or moving horizontally aplatform on which the means of visible light radiation is secured; andother means. The information on the directions of radiation, which isstored in the means of storage, may include, for example, a horizontalangle, a vertical angle, or other information. Of course, controlvalues, such as the amount of displacement, may also be included, aswell as the angles. As the means of controlling the radiationdirections, for example, a computer, an application specificsemiconductor device, or other electronic circuits may be used.

[0145] (24) A system for interfering against image capturing is proposedin which a visible light for the interference passes through a spaceoutside of the screen and is directly radiated on the viewer. Thissystem represents an application example for the method described in(9). For this reason, the descriptions in (9) may apply on the presentsystem. Since the visible light for the interference is required to passthrough a space outside of the screen, the position of the visible lightradiation apparatus, which radiates the visible light for theinterference, can be at any location. For example, the location may bebehind the screen, or the location may in front of the screen. Ofcourse, the location may also be around the screen.

[0146] (25) A system for interfering against image capturing isproposed, which radiates a visible light for the interference from ameans of radiating the visible light at the back side of a screen andtransmits the visible light for the interference through the screentoward the viewer. The present system represents an application examplefor the method described in (10). Several forms of transmission arepossible, depending on the material and structure of the screen.

[0147] (26) A system for interfering against image capturing is proposedin which a visible light for the interference, which is radiated by ameans of radiating the visible light at the backside of the screen,passes through a passing part in the screen toward the viewer. Thepresent system represents an application example of the method describedin (11). In this instance also, several forms of the passing parts ofvarious shapes and structure are possible.

[0148] (27) A system for interfering against image capturing is proposedin which a visible light for the interference is emitted by a means ofradiating the visible light, which is embedded inside a screen, towardthe viewer from the screen surface. The present system represents anapplication example for the method described in (12). The method ofembedding and the forms of the output for the visible light for theinterference are similar to the description in (12).

[0149] (28) A system for interfering against image capturing isproposed, that includes a plurality of units of means of radiating thevisible light, and a means of control for the means of radiating thevisible light provides as an output the visible lights for theinterference in prescribed combinations at a plurality of locations onthe screen, so that a two dimensional optical image pattern may besimultaneously recorded, when an image on the screen is illegally imagecaptured. The present system is an application example for thedescription in (13). The conditions and the structures required for thebasic configurations for the various means are similar to (20).

[0150] (29) A system for interfering against image capturing is proposedwhen an image being presented on a screen by a projection method using afilm based means of projection. The image capturing interference systemincludes a means of radiating a visible light for radiating a whitecolor light for the interference from target image pixels on the screen;a shutter cycle detection means for detecting the time periods duringwhich a frame forwarding shutter shutters the projected light; a meansof calculation for determining a luminance of the white color light forthe interference based on an average luminance in a previous frame andan ensuing frame in the target image pixels; and a means of control forprojecting the white color light for the interference from the targetimage pixels during the time period in which the projection light isshuttered. The present system is an application example for thedescription in (14).

[0151] The same means of detecting the shuttered cycles, the means ofcalculation, and the means of control as those in (21), respectively,may be used. The only difference from (21) is the method of radiatingthe white color light for the interference.

[0152] (30) A system for interfering against image capturing is proposedwhen an image being presented on a screen by a projection method using afilm based means of projection. The image capturing interference systemincludes a means of radiating the visible light for radiating a visiblelight for the interference from target pixels on the screen; a shuttercycle detection means for detecting the time periods during which aframe forwarding shutter shutters the projection light; a means ofcalculation for determining a luminance and a chromaticity of thevisible light for the interference based on an average luminance and anaverage chromaticity in a previous frame and an ensuing frame in thetarget image pixels; and a means of control for projecting the visiblelight for the interference from the target image pixels during the timeperiod in which the projection light is shuttered. The present system isan application example for the method described in (15).

[0153] The same means of detecting the shuttered periods, the means ofcalculation, and the means of control as those in (22), respectively,may be used. The only difference from (22) is the method of radiatingthe white color light for the interference.

[0154] (C) Actual Embodiments

[0155] Specific embodiments for the methods and systems for interferingagainst image capturing, that are proposed in the present specification,will be described next.

[0156] (1) First Embodiment

[0157] The first embodiment is shown in FIG. 18. The present embodimentis related to an invention of a method of projecting a visible light(including a white color light) for the interference from the front of ascreen (on the side of an audience) toward the screen. FIG. 18 shows anapplication example in a movie theater or other types of theatersystems. It goes without saying that the technology itself may beapplied on a home theater. In any of these instances, the imageprojected onto the screen may include not only movies but alsotelevision programs and other copyrighted materials. Specific examplesof various apparatuses that make up the system, which are shown in FIG.18, will be described next.

[0158] A projector apparatus 33 is a projection apparatus for projectingan image to be viewed onto a screen 34. The projector apparatus 33 maybe, for example, a film projector for projecting a movie film; a slideprojector for projecting a slide; an overhead projector (OHP); a liquidcrystal projector that directly projects a digital image; a digitalmicromirror device (DMD) projector; a CRT projector, or others.

[0159] In FIG. 18, the projector apparatus 33 is placed on the back sideof the seats 36, and the audience views a reflected light from thescreen surface. However, the position of the projector apparatus 33 isnot limited to this. For example, the projector apparatus 33 may beplaced in front of the seats 36 (or between the screen 34 and the seats36), above the seats 36, or on a side wall. Of course, with the methodof projecting the image from the back side of the screen to make theaudience view a transmitted light (or in a case of a rear projectionmethod), the projector apparatus 33 may be placed behind the screen 34.

[0160] The screen 34 in FIG. 18 is a screen for a theater. In general,holes for sound sources (through holes or other structures, thatcommunicate the back side with the front side and are called soundperforation,) are formed in order to efficiently transmit sound fromsources of the sound, which are placed behind the screen, toward theaudience. The screen, however, does not need to have holes for the soundsources.

[0161] The visible light radiation apparatus 35 for the interference isan apparatus for radiating a visible light, that satisfies the condition1 and the condition 2, in order to interfere against an illegal imagecapturing of the image projected on to the screen. The radiationapparatuses, having the structure shown in, for example, FIG. 4 or FIG.5, are used as this apparatus. In FIG. 18, the visible light radiationapparatus 35 is set up alongside the projector apparatus 33, but anapparatus configuration that is combined with the projector apparatus isalso possible. The visible light radiation apparatus 35 may also have anability to project the visible light for the interference on a pluralityof spots on the screen. Although not shown in FIG. 18, the synchronizingapparatus, which was shown in FIG. 12 and FIG. 13, is connected to thevisible light radiation apparatus 35. In general, the visible lightradiation apparatus 35 may be placed in such a way as to face thescreen, but a position in front of the screen at an angle is alsopossible.

[0162] In the figure, the visible light, radiating from the visiblelight radiation apparatus 35, is directly radiated on the screensurface. However, an optical beam, that is reflected off a reflectivemirror, may also be projected on to prescribed areas on the screen. Ahigher degree of freedom is allowed for the position of the visiblelight radiation apparatus 35, when the optical path for the visiblelight is bent using a reflection mirror. Or, the visible light radiationapparatus 35 itself may be driven for directing the radiation of thevisible light toward a prescribed area or space.

[0163] By the way, it is also possible to use the plurality of opticalimage patterns, that are projected onto the screen, in order to recordprescribed information (for example, the output time and date, theoutput location, the screen number, the output apparatus, and otherinformation required for identifying the individual making the outputand the location of the illegal activity) or text based information(symbols and other recognizable geometrical information). In such aninstance, in general, a plurality of units of the visible lightradiation apparatus 35 are collectively operated. When such a functionis to be implemented, a means of table (a means of storage) may be usedfor storing the correlation between the optical image patterns forshowing the desired information and the plurality of visible lightradiation apparatuses, which generate them.

[0164] The visible light that provides the information may, in general,be emitted continuously (turning light on), but the prescribedinformation may also be provided using a method of emitting the visiblelight intermittently.

[0165] In addition, the method of projecting the visible light includesa method of emitting the visible light intermittently. When the visiblelight is projected intermittently, the luminance of the image beingrecorded may change independently of the image being presented and thusdegrades the image quality. Furthermore, changes in the intermittenttiming and the recorded positions for the optical images may make thedesired information be recorded.

[0166] The number of the visible light radiation apparatuses 35 is notlimited to one unit. Although a single unit of the visible lightradiation apparatus 35 is shown in FIG. 18, two or more units of thevisible light radiation apparatuses may also be installed.

[0167] By radiating the visible light for the interference from theaudience toward the screen according to the present embodiment, it ispossible to make the desired information on, for example, the locationthe image capturing be recorded simultaneously with the image that hasbeen illegally captured. Accordingly, the image quality can also be madeto degrade. As a result, an interference effect comparable to but notusing an infrared light can be achieved.

[0168] (2) Second Embodiment

[0169]FIG. 19 shows the second embodiment. This embodiment is related toan invention on a method of projecting a visible light for theinterference (including the white color light) from the back side of ascreen toward the screen. FIG. 19 also shows application examples inmovie theaters and other theater systems. Of course, the technologyitself may be applicable on a home theater. In any of these instances,the image being projected onto the screen may include not only moviesbut also television programs and other copyrighted materials. Specificexamples of the various apparatuses that make up this system, which areshown in FIG. 19, will be described next. The projector apparatus 33will not be described since it is similar to the first embodiment.

[0170] The screen 34 is a screen for a theater. In general, holes forsound sources (through holes that communicate between the back side andthe front side or other structures), which are called sound perforation,are formed in order to efficiently transmit the sound from sources ofthe sound, which are placed behind the screen, toward the audience. Anyshapes, sizes, and locations may be allowed for the sound perforation.In the specification of the present application, the sound perforationis used as passing parts for allowing the visible light for theinterference to pass from behind the screen to the front of the screen.

[0171] By the way, the screen 34 in FIG. 19 does not need to include thesound perforation. In such an instance, however, the screen itself isdesirable to be made of a material that may easily allow the visiblelight to transmit through; include embedded members that may easilyallow the visible light to transmit through; or include areas that arethinner than other areas.

[0172] The visible light radiation apparatus 35 is an apparatus forradiating the visible light for interfering against an illegal imagecapturing of the image that is projected onto the screen. By the way, aninternal configuration of the visible light radiation apparatus 35 isthe same as in the first embodiment.

[0173] The visible light radiation apparatus 35 is, in general, locatednear the back side of the screen. However, any location may be allowed,as long as the location is behind a hypothetical reference surface,which includes the screen surface, with respect to the seats 36. Forexample, the visible light radiation apparatus 35 may be placed behindthe screen 34 at an angle. By the way, the point of emission may be incontact with the screen, or the point of emission may be embedded intothe screen. The point of emission, that is embedded into the screen, maybe exposed at the surface of the screen toward the front.

[0174] In the figure, the visible light that is radiated from thevisible light radiation apparatus 35 is directly radiated on to thescreen surface. However, as shown in FIG. 20, a beam of light reflectingoff a reflection mirror 37 may be projected at prescribed areas on thescreen. A higher degree of freedom may be allowed for the position ofthe visible light radiation apparatus 35, when the reflection mirror isused for bending the optical path for the visible light. Furthermore,instead of reflecting the visible light through the means of reflection,the visible light radiation apparatus 35 itself may be driven to directthe direction of radiation for the visible light toward the prescribedarea or space, as mentioned earlier.

[0175] Even in such an instance, prescribed information or textinformation may be recorded using a plurality of optical image patternsprojected onto the screen. Normally, a plurality of units of the visiblelight radiation apparatus 35 are collectively operated. In order torealize this feature, a means of table (means of storage) is used forstoring relationships of correlation between the optical image patterns,that represent the desired information, and the plurality of units ofthe visible light radiation apparatus that generate them.

[0176] In general, the visible light that provides this information islit on continuously (turning light on), but it is also possible topresent the prescribed image using a method of intermittently emittingthe visible light.

[0177] Furthermore, the method of projecting the visible light includesa method of intermittently emitting the visible light. When the visiblelight is projected intermittently, the luminance of the image beingrecorded changes independently of the image being presented and thusdegrades the quality of the image. By the way, a recording of desiredinformation can also be facilitated by making the timings ofintermittence and the recording positions of the optical imagesvariable.

[0178] The number of units of the visible light radiation apparatus 35is not limited to a single unit. Although a single unit of the visiblelight radiation apparatus 35 is shown in FIG. 20, it is also possible touse two or more units of the visible light radiation apparatuses.

[0179] By radiating the visible light for the interference onto thescreen from behind the screen, as in the present embodiment, it ispossible to have the desired information, that shows, for example, thelocation of the image capturing, be recorded in the image that has beencaptured illegally. Accordingly, it is also possible to degrade thequality of the image. As a result, it is possible to realize aninterference effect similar to but not using the infrared light.

[0180] (3) Third Embodiment

[0181]FIG. 21 shows the third embodiment. The present embodiment isrelated to an invention on a method of radiating a visible light for theinterference from a screen periphery toward the audience. In an exampleshown in FIG. 21, the visible light radiation apparatus 35 is placedoutside of an upper side of a screen 34 (above). FIG. 21 also representsan application example in a movie theater and other theater systems. Ofcourse, the technology itself is also applicable on a home theater. Theimage being projected onto the screen not only includes movies but alsotelevision programs and other copyrighted materials.

[0182] Next, specific examples of the various apparatuses, that make upthe system shown in FIG. 21, will be described. Because the projectorapparatus 33 is similar to the embodiments described earlier, it willnot be described. A screen 34 is also similar to the previousembodiment.

[0183] The visible light radiation apparatus 35 has a similar apparatusconfiguration as the previous embodiment. The position of and aprojection method used for the visible light radiation apparatus 35 aredifferent. By the way, the visible light being radiated from a positionoutside of the screen, as in the present embodiment, is required tosatisfy the condition 1 and condition 2 with respect to a backgroundlight, so that the visible light for the interference may not bedetected during a normal viewing.

[0184] The position of the visible light radiation apparatus 35 isusually near an outer edge of the screen. The closer it is to an area,onto which the image being presented is projected, the more likely thevisible light, that is being projected, may be recorded, because thevisible light may be within a field of image capturing, be recordeddirectly, and more likely affect the field of image capturing. A moresignificant interference effect is thus achieved. However, theinterference effect may not necessarily be less significant in aposition that is further outside of the edge of the screen.

[0185] In such an instance, a means of reflection may be used to bendthe optical path for the visible light for the interference. When areflection mirror is used for bending the optical path for the visiblelight, a higher degree of freedom is allowed for the position of thevisible light radiation apparatus 35. Furthermore, as described earlier,instead of reflecting the visible light through a means of reflection,the visible light radiation apparatus 35 itself may be driven to directthe radiation of the visible light toward the above-mentioned prescribedarea or space.

[0186] The visible light that provides this information is, in general,emitted continuously (turning light on). However, a prescribedinformation may also be provided by a method of emission, in which thevisible light is emitted intermittently.

[0187] In addition, the method of projecting the visible light includesa method of emitting the visible light intermittently. When the visiblelight is projected intermittently, the luminance of the image beingrecorded may change independently of the image being presented and thusdegrade the quality of the image. By the way, desired information can bemade to be recorded by making the timings of intermittence and therecording positions of the optical images variable.

[0188] Furthermore, the number of the visible light radiation apparatus35 is not limited to a single unit. While FIG. 21 shows a single unit ofthe visible light radiation apparatus 35 being used, two or more unitsof the visible light radiation apparatus may also be used.

[0189] When the visible light for the interference passes through aspace outside of the screen and is radiated toward the audience, as inthe present embodiment, it is possible to have the desired information,that shows, for example, the location of the image capturing, berecorded into the image that has been illegally captured. Of course, itis also possible to degrade the quality of the image. As a result, aninterference effect similar to but not using the infrared light can berealized.

[0190] (4) Fourth Embodiment

[0191]FIG. 22 shows the fourth embodiment. The present embodimentrelates to an invention on a method of radiating the visible lights forthe interference during the times in which the frame forwarding shuttershuts out the projected light. FIG. 22 shows examples of applications inmovie theaters and other theater systems. However, like the otherembodiments, the technology itself can be applied on a home theater. Ofcourse, the image being projected onto the screen is not limited tomovies but also includes television programs and other copyrightedmaterials.

[0192] Next, specific examples of various apparatuses, that make up thesystem shown in FIG. 22, will be described. The system shown in FIG. 22,like the system in the second embodiment, includes a visible lightradiation apparatus 35 for the interference, that is placed behind ascreen 34 (or embedded in the screen 34). In this respect, the presentembodiment is an example of the second embodiment. Therefore, the sameprojector apparatus 33 and the screen 34 as the second embodiment areused. By the way, the technology related to the present embodiment mayalso be applicable on the visible light being radiated from the front ofthe screen onto the screen.

[0193] In the present embodiment, a surface of the screen is dividedinto 28 virtual partial areas, which make up four columns and sevenrows. One unit of the visible light radiation apparatus 35 is placed foreach partial area.

[0194] A shutter sensor 38 is effective in a film based projectorapparatus, which is used as a projector apparatus 33. Therefore, thistype of shutter sensor 38 may not exist in the projector apparatus 33that is based on a digital signal format. The shutter sensor 38 is usedfor projecting the visible light for the interference onto the screenduring the time period, in which the shutter 42 in the film basedprojector apparatus (i.e. a movie projector) shutters the projectionlight.

[0195]FIG. 23 shows a representative configuration example for thisfeature. The movie projector projects an image onto the screen through arepetition of a step for projecting the image onto the screen byradiating an optical source light 41, while a film 40 is stationary inan aperture (a window for projecting the film in the projector); and astep in which the optical source light 41, that is radiated on the film40, is shuttered, and, during which time, the film is frame forwarded.The lens 43 in the figure is a projection lens for projecting theoptical source light onto the screen 34.

[0196] In general, the shutter 42 for shuttering the optical sourcelight is a disc with slits. Normally, the slits are formed at twosymmetrical positions on the disc. Normally, the disc rotates 24 timesin each second and shuts out the optical source light twice for eachframe (FIG. 24(B)). An intersprocket 44 forwards the film 40 by oneframe during a period, in which one of the two times the light isshuttered for each frame (FIG. 24(A)). As a result, the visible lightradiation apparatus 35, which runs in conjunction with the shutter 42with the same operation timing, radiates the visible light once perframe (FIG. 24(C)).

[0197] By the way, the luminance and chromaticity of the visible lightbeing radiated satisfy the condition 1 and the condition 2 with respectto a background light, which is assumed to have an average luminance andan average chromaticity between a previous frame and an ensuing frame.For this reason, the visible light may have a luminance of a valuebetween 0% and 100%.

[0198] The shutter sensor 38 may operate based on an optical method, aswell as an electronic method or a mechanical method. For example, amethod shown in FIG. 25 may be used for the optical method. FIG. 19shows a method of identifying positions (rotational positions), at whichthe shutter 42 shutters the optical source light, using a beam of lightreflecting off the shutter surface. FIG. 25(A) shows the optical sourcelight 41 being projected, FIG. 25(B) shows the shutter 42 starting toshutter the light, and FIG. 25(C) shows the shutter 42 shuttering theoptical source light 41.

[0199] When the method shown in FIG. 25 is used, the shutter sensor 38is placed in such a way as to face the blades of the shutter 42, whenthe light is shuttered. The shutter sensor 38 may, for example, be alight emitting diode (a means of light emission) and a photo diode (ameans of receiving light), which are placed on a surface that faces theshutter 42, for example. By adopting such a layout, it may be possibleto detect the relative positions of the shutter, because a large volumeof light may be received by the photo diode, when the optical sourcelight is shuttered, while the volume of light may go down duringprojection.

[0200] Furthermore, the optical based method also includes a method inwhich the light emitting diode and the photo diode are placed in such away as to face each other while sandwiching the rotating area of thedisc, and the relative position of the shutter 42 (rotation position) isdetected based on whether or not a beam of light radiating from thelight emitting diode is received by the photo diode. In this instance,the rotation position of the disc can be detected based on the timingswith which the light, which emits from the light emitting diode, isreceived by the photo diode or shuttered from the photo diode.

[0201] In addition, the shutter sensor 38 may rely on a method ofmechanically detecting the rotational position of the disc. For example,the rotational position of the shutter may be mechanically detectedbased on the rotational position of a gear (the position of teeth),which is attached coaxially with respect to the rotation axis. In yetanother example, electrodes may be installed, with the rotating area ofthe disc sandwiched in between, and the detection method may be based onmeasuring the changes in the static capacitance between the electrodesin order to detect whether a blade in the disc or a gap is between theelectrodes. Furthermore, another method is possible in which therotational position of the shutter is detected based on the informationrelated to the drive of the rotation axis.

[0202] Furthermore, it goes without saying that, when the shape of theshutter varies or the method of the shutter varies, an appropriate formof the shutter sensor 38 may be used in response to the shapes or theforms. For example, when the opening and closing of the shutter iscontrolled electronically, then the periods, during which the opticalsource light is shuttered, may be detected based on a method that relieson the signals for the opening and the closing.

[0203] A method of using a detection result may include a method inwhich an infrared light is emitted, when a closing of the shutter isdetected, or a method in which the closing of the shutter is predictedbased on the detected results, and the infrared light is emitted basedon a predicted timing.

[0204] The visible light radiation control apparatus 39 is a means ofcontrolling the light emitted by the visible light radiation apparatus35 based on the shutter information S1, which is received from theshutter sensor 38. In the present embodiment, a process of determiningthe luminance and the chromaticity of the visible light being radiatedis executed by the visible light radiation apparatus 35. It is alsopossible, by the way, to have the visible light radiation controlapparatus 39 execute the process of determining the chromaticity and theluminance.

[0205] The internal configuration of the visible light radiation controlapparatus 39 varies in response to the application system. For example,as shown in FIG. 22, a computer, that consists of a processor unit,which includes a control apparatus and an arithmetic apparatus, a memoryapparatus, and an input and output apparatus, may in general be used fora system that may completely control the visible light radiationapparatus 35. However, it is also possible to realize the functionsprovided by a program, that is executed by the computer, by using,instead, an electronic circuit.

[0206] For example, a desired interference effect may be realized,without using a control apparatus, by simply using the detection resultsfrom the shutter sensor 38 as a control signal for turning on or off thevisible light radiation apparatus 35.

[0207] Returning to the instance in which the visible light radiationcontrol apparatus 39 is used. For example, when the shutter sensor 38detects a closing of the shutter (or the projection light beingshuttered), the visible light radiation control apparatus 39 may providea control signal S2, as an output to send an instruction to the visiblelight radiation apparatus 35 to radiate the visible light. In thisinstance, the visible light radiation control apparatus 39 may instructall of the visible light radiation apparatuses to radiate the visiblelight (in the example in FIG. 22, the instruction may be sent to all 28units of the visible light radiation apparatuses). On the other hand,the visible light radiation control apparatus 39 may also send aninstruction to radiate the visible light only to some of the visiblelight radiation apparatuses. In the example in FIG. 22, for instance,the instructions for radiating the visible light may be sent in such away that the emitted light pattern may be in a checker pattern.Furthermore, the instruction for projecting the infrared light may beprovided to make the emitted light patterns form another recognizablegeometric pattern, such as a character or a symbol.

[0208] An effect similar to superimposing the visible light for theinterference onto the image being projected can also be realized by thevisible light for the interference, including the white color light,that is emitted only during the periods of frame forwarding, as in thepresent embodiment.

[0209] (5) Fifth Embodiment

[0210]FIG. 26 shows the fifth embodiment. The present embodiment is avariation of the embodiment described earlier. The present embodiment ischaracterized in that the information related to the time and area ofprojection for the visible light for the interference, as well asinformation related to the luminance and the chromaticity of the visiblelight for the interference, is obtained through a recording medium or anetwork, as needed.

[0211] In FIG. 26, the image being presented is projected from the frontof the screen, while the visible light for the interference is radiatedfrom behind the screen. Of course, this figure represents only a singleexample, and the present embodiment is applicable on the image beingpresented that is projected from behind the screen, as well as thevisible light for the interference projected from the front of thescreen. Only the configuration of the apparatus that is specific to thepresent embodiment will be described next.

[0212] A program server 45 is an apparatus for feeding out the imagedata S3 to the projector apparatus 33. The image data S3 may includedata read out from a recording medium 46 (which may include, forexample, a videotape, a CD-ROM, a DVD, etc.) as well as data receivedthrough a network 47. Such an output of the image data S3 may not takeplace, however, when the projector apparatus 33 is a film basedprojector apparatus.

[0213] The program server 45 reads out the information related to thetiming or the information related to the positions of partial areas, onwhich the visible light radiation may be applied, by functioning as anapparatus for reproducing information from the recording medium 46 or byfunctioning as an apparatus for receiving data from the network 47. Inother words, the program server 45 also functions as an apparatus forfeeding out the visible light radiation control data S4 into the visiblelight radiation control apparatus 39. By the way, the recording mediummay be those provided through a postal service or a home deliveryservice or a recording of the data received in advance through adistribution over the network 47. Furthermore, the visible lightradiation control data S4 may include information related to therelationships between the chromaticity and the luminance of the visiblelight.

[0214] In this instance, the image data S3, which is fed to theprojector apparatus 33, and the visible light radiation control data S4,which is fed to the visible light radiation control apparatus 39, aresynchronized by the program server 45. Of course, the synchronization ofthe data is controlled based on a common synchronization data orinformation related to the timing of the data reproduction in a digitalformat projection system. By the way, the timing of the output for thevisible light radiation control data S4 is controlled based onsynchronization signals and information related to positions, which areread from a film, as well as information related to the rotationalposition of the shutter 42, if the projector apparatus 33 is film based.

[0215] The visible light radiation control apparatus 39 is a means ofactually controlling the emission of light from the visible lightradiation apparatus 35. Similar to the sixth embodiment, the visiblelight radiation control apparatus 39 may instruct all units of thevisible light radiation apparatuses 35 to radiate the visible light orprovide instructions to only some of the visible light radiationapparatuses 35 to radiate the visible light.

[0216] An effect similar to the previous embodiments is realized bycontrolling the emission of the visible light for the interference usingdata read from a recording medium or data received through a network, asin the present embodiment.

[0217] (6) Sixth Embodiment

[0218]FIG. 27 shows the sixth embodiment. The present embodimentrepresents an application example in which the directions of radiationfor the visible light is automatically adjusted in response to changesin the screen size, which are dependent on the contents. In FIG. 27, asystem combines the present invention and the fourth embodimentdescribed earlier (invention in which the timing of the emission of thevisible light is controlled based on information related to theshutter), and the fifth embodiment (invention in which the timing of theemission of the visible light is controlled based on the visible lightradiation control data).

[0219]FIG. 27 also shows applications examples in a movie theater orother types of theater systems. As in the other embodiments, thetechnology itself is also applicable on a home theater. Of course, theimage being projected onto the screen may include not only movies butalso television programs and other copyrighted materials.

[0220] Firstly, the method of positioning the visible light radiationapparatus 35 will be described. In FIG. 27, the visible light radiationapparatus 35 is placed at a position that is slightly in front of thescreen peripherally (For example, at an outer edge of the screen or inan area outside of the frame). Of course, the visible light radiationapparatus 35 may be placed at any position, including a position thatdirectly faces the screen, and does not need to be near the screen, aslong as the position is in front of the screen. Furthermore, the visiblelight radiation apparatus 35 may be placed at any arbitrary positionbehind the screen as well.

[0221] In FIG. 27, seven units of the visible light radiationapparatuses 35 are placed along the top edge and bottom edge of thescreen, along the longer side direction of the screen (the transversedirection). Furthermore, four units of the visible light radiationapparatuses 35 are placed on the right hand edge and the left hand edgeof the screen, along the shorter side direction of the screen (thelongitudinal direction). On the other hand, the visible light radiationapparatuses 35 may also be placed on only one of the edges, or thevisible light radiation apparatuses 35 may be placed on any two of theedges, or the visible light radiation apparatuses 35 may be placed onany three of the edges. Of course, any number of units of the visiblelight radiation apparatuses 35 may be placed.

[0222] The apparatuses that are characteristic to the system shown inFIG. 27 will be described next. Other apparatuses, which are common tothe other embodiments, will not be described in particular. There aretwo apparatuses that are characteristic, which are the radiationdirection drive apparatus 48 and a screen mask change apparatus 49.These apparatuses are used for automatically adjusting the directionsand positions of the radiation of the infrared light in conjunction withswitching of screen sizes, when there is a plurality of screen sizes incorrespondence with the images being projected.

[0223]FIG. 28 shows an example of how the visible light radiationapparatus 35 may be attached on to the radiation direction driveapparatus 48. In FIG. 28, the radiation direction drive apparatus 48 isattached on to the rear side of the visible light radiation apparatus35, or on the side that is opposite from the direction of projection ofthe visible light, and can turn freely. The axis of turning isorthogonal to the direction of the optical axis. The visible lightradiation apparatus 35 is linked to a motor in the radiation directiondrive apparatus 48 through, for example, gears and is attached in such away that the visible light radiation apparatus 35 may turn by aprescribed angle in a prescribed direction in response to an amount ofmotor rotation.

[0224] The means of drive, however, is not limited to a method in whicha force is transmitted based on an amount of rotation and may include amethod in which a force is transmitted based on an amount ofdisplacement in a linear direction. Furthermore, the means of drive maybe applied directly on the visible light radiation apparatus 35 orapplied indirectly through linking devices, which may include gears,rubbers, and others. Furthermore, while the displacement takes place inonly one direction in FIG. 28, the displacement may also take place intwo directions. For example, the displacement may made be possible intwo directions that include the horizontal direction and the verticaldirection.

[0225] The screen mask change apparatus 49 is a means of automaticallyfeeding the information related to the drive control for the visiblelight radiation apparatus to the radiation direction drive apparatus 48in response to an instruction to change the screen size. For example,the screen mask change apparatus 49 may include a memory unit thatstores information (for example, information related to the direction ofradiation or angle) that correlates the screen size and thecorresponding projection directions for the infrared projectionapparatus, and a control unit that reads out appropriate numericalvalues for the new screen size, when the screen size is changed, fromthe memory unit, and feeds the information to the radiation directiondrive apparatus 48 for the various positions. If the informationprovided as an output to the radiation direction drive apparatus 48 werenot the target values (the optimal values), as in the present example,then the amount of adjustment (a differential value) with respect to thepresent value, may be calculated and provided. One of these data isprovided by the screen mask change apparatus 49 to the radiationdirection drive apparatus 48 as the control data S6 output.

[0226] By the way, instructions related to changes in the screen size orinformation on the optimal screen size may, in some cases, be providedin conjunction with a manual operation by an operator or, in othercases, provided automatically based on information recorded inassociation with the image contents. In a movie theater, for example,the operator at the theater operates buttons for changing the positionof the mask, when the screen size, or the aspect ratio, changes. Thesame button operation may also be used for manipulating a change in thedirection of the projection. Or, as in the latter case, in which therecorded information is to be used, the optimization information may berecorded either in the media itself, that stores the image contents, orin another recording medium, that is separate from the image contents,in a form of a mapping table.

[0227] While in FIG. 27 the radiation direction drive apparatus 48 andthe screen mask change apparatus 49 are represented as separate units,it is also possible to combine the two into a single apparatus. Theadjustment of the direction of the radiation for the infrared light maybe performed for each visible light radiation apparatus or by rows or byfew adjacent units of the visible light radiation apparatuses.

[0228] By automatically adjusting the direction of the projection forthe visible light in response to the screen size, as in the presentembodiment, it is possible to avoid the projection positions of thevisible light and the image contents from being out of synchronicity. Bythe way, a similar effect can be realized by controlling the luminanceinformation and the chromaticity information for the visible light, thatis fed to the visible light radiation apparatus, instead of controllingthe direction of projection for the visible light.

[0229] (7) Seventh Embodiment

[0230] In the various embodiments described above, representative andspecific examples of the conceptual embodiments are reviewed. Systemsthat combine the various embodiments described above or other examplesof variation are also possible.

[0231] By using the visible light that satisfies the condition 1 and thecondition 2, as mentioned above, it is possible to make an opticalimage, that is unrelated to the image being presented, be superimposedwith and recorded in an illegally captured version of the image on thescreen, although the optical image may not be visible to the audience inthe normal viewing. As a result, it is possible to interfere against anillegal image capturing activity.

1. A method of interfering against image capturing, characterized inthat a visible light for the interference, that satisfies the conditionsbelow, is radiated onto a screen so as to prevent the image on thescreen from being illegally captured: (1) Because of the human visioncharacteristics, an optical image for the visible light for theinterference is difficult to distinguish from the image being projectedonto the screen. (2) Because of the characteristics of a means of imagecapturing, an optical image for the visible light for the interferenceis recorded and distinguishable from the image on the screen, when theimage on the screen is illegally image captured.
 2. The method ofinterfering against image capturing of claim 1 characterized in that thevisible light for the interference is a composite light consisting of aplurality of single colored lights, which have different chromaticities.3. The method of interfering against image capturing of claim 1characterized in that a chromaticity and a luminance of the visiblelight for the interference is variably controlled in response to theimage being presented and projected onto the screen.
 4. The method ofinterfering against image capturing of claim 1 characterized in that achromaticity of the visible light for the interference is controlled tomatch a chromaticity of the image being presented, that is projectedonto an identical area as an optical image for the visible light.
 5. Themethod of interfering against image capturing of claim 1 characterizedin that a luminosity of the visible light for the interference iscontrolled to be lower than or substantially equal to an incrementthreshold of the human contrast sensitivity, which is calculated from aluminance at an area of the image onto which the visible light isprojected for superimposition.
 6. The method of interfering againstimage capturing of claim 1 characterized in that the visible light forthe interference is radiated from a viewer's side onto the screen, and areflected light that is reflected off the screen is used for interferingagainst the illegal activity.
 7. The method of interfering against imagecapturing of claim 1 characterized in that the visible light for theinterference is radiated from behind the screen, and a transmitted lightthat transmits through the screen toward a viewer's side is used forinterfering against the illegal activity.
 8. The method of interferingagainst image capturing of claim 1 characterized in that the visiblelight for the interference is radiated from behind the screen, and apassing light, which passes through a passing part in the screen andtravels toward a viewer's side, is used for interfering against theillegal activity.
 9. The method of interfering against image capturingof claim 1 characterized in that the visible light for the interference,which is radiated onto the screen, is a beam of light that is reflectedoff a means of reflection.
 10. The method of interfering against imagecapturing of claim 1 characterized in that the visible lights for theinterference in a prescribed combination are projected onto a pluralityof locations on the screen, so that a secondary optical image pattern isrecorded simultaneously, when the image on the screen is illegally imagecaptured.
 11. The method of interfering against image capturing of claim1 characterized in that, when the image being presented is projectedonto the screen by a film based means of projection, a white color lightfor the interference, a luminance in a target image pixel of which isdetermined based on an average luminance between a preceding frame andan ensuing frame, is radiated onto the target image pixel on the screenduring a time period in which a frame forwarding shutter shutters aprojection light.
 12. The method of interfering against image capturingof claim 1 characterized in that, when the image being presented isprojected onto the screen by a film based means of projection, thevisible light for the interference, determined based on an averagechromaticity and average luminance between a previous frame and anensuing frame at a target image pixel, is radiated onto the target imagepixel on the screen during a time period in which a frame forwardingshutter shutters a projection light.
 13. The method of interferingagainst image capturing of claim 1 characterized in that, when a screensize is changed, a direction of radiation of the visible light for theinterference is automatically adjusted.
 14. A method of interferingagainst image capturing characterized in that a visible light for theinterference, that satisfies the conditions below, is radiated from ascreen side to a viewer side so as to interfere against an image on thescreen from being illegally image captured. (1) Because of the humanvision characteristics, an optical image for the visible light for theinterference is difficult to distinguish from an image being projectedonto the screen. (2) Because of the characteristics of a means of imagecapturing, an optical image for the visible light for the interferenceis recorded and distinguishable from the image on the screen, when theimage on the screen is illegally image captured.
 15. The method ofinterfering against image capturing of claim 14 characterized in thatthe visible light for the interference is a composite light consistingof a plurality of single colored lights, which have differentchromaticities.
 16. The method of interfering against image capturing ofclaim 14 characterized in that a chromaticity and a luminance of thevisible light for the interference is variably controlled in response tothe image being presented and projected onto the screen.
 17. The methodof interfering against image capturing of claim 14 characterized in thata chromaticity of the visible light for the interference is controlledto match a chromaticity of the image being presented, that is projectedonto an identical area as an optical image for the visible light. 18.The method of interfering against image capturing of claim 14characterized in that a luminousity of the visible light for theinterference is controlled to be lower than or substantially equal to anincrement threshold of the human contrast sensitivity, which iscalculated from a luminance at an area of the image onto which thevisible light is projected for superimposition.
 19. The method ofinterfering against image capturing of claim 14 characterized in thatthe visible light for the interference passes through a space outsidethe screen and is directly radiated toward the viewer side.
 20. Themethod of interfering against image capturing of claim 14 characterizedin that the visible light for the interference is radiated out of anoptical source at a back side of the screen, transmits through thescreen, and travels to the viewer side.
 21. The method of interferingagainst image capturing of claim 14 characterized in that the visiblelight for the interference is radiated out of an optical source at abackside of the screen, and passes through a passing part in the screen,and travels to the viewer side.
 22. The method of interfering againstimage capturing of claim 14 characterized in that the visible light forthe interference is radiated out of an optical source embedded in thescreen and emitted from a surface of the screen toward the viewer side.23. The method of interfering against image capturing of claim 14characterized in that the visible lights for the interference in aprescribed combination are projected onto a plurality of locations onthe screen, so that a secondary optical image pattern is recordedsimultaneously, when the image on the screen is illegally imagecaptured.
 24. The method of interfering against image capturing of claim14 characterized in that, when the image being presented is projectedonto the screen by a film based means of projection, a white color lightfor the interference, a luminance in a target image pixel of which isdetermined based on an average luminance between a preceding frame andan ensuing frame, is radiated from the target pixel on the screen duringa time period in which a frame forwarding shutter shutters a projectionlight.
 25. The method of interfering against image capturing of claim 14characterized in that, when the image being presented is projected ontothe screen by a film based means of projection, the visible light forthe interference, determined based on an average chromaticity andaverage luminance between a previous frame and an ensuing frame at thetarget image pixel, is radiated out of the target pixel on the screenduring a time period in which a frame forwarding shutter shutters aprojection light.
 26. A system for interfering against image capturingcharacterized in that the system includes a visible light radiationmeans for radiating a visible light for the interference that satisfiesthe conditions below, and the visible light for the interference isradiated onto the screen so as to interfere against an image on thescreen from being illegally image captured: (1) Because of the humanvision characteristics, an optical image for the visible light for theinterference is difficult to distinguish from an image being projectedonto the screen. (2) Because of the characteristics of a means of imagecapturing, an optical image for the visible light for the interferenceis recorded and distinguishable from the image on the screen, when theimage on the screen is illegally image captured.
 27. The system forinterfering against image capturing of claim 26 characterized in thatthe visible light radiation means outputs a composite light consistingof a plurality of single colored lights, that have differentchromaticities, as the visible light for the interference.
 28. Thesystem for interfering against image capturing of claim 26 characterizedby further including a control means for variably controlling achromaticity and a luminosity of the visible light for the interferencein response to the image being presented that is projected onto thescreen.
 29. The system for interfering against image capturing of claim26 characterized by further including a control means for controlling achromaticity of the visible light for the interference in such a way asto match a chromaticity of the image being presented, which is projectedonto an identical area of an optical image for the visible light for theinterference.
 30. The system for interfering against image capturing ofclaim 26 characterized by further including a control means forcontrolling a luminance of the visible light for the interference tolower than or substantially equal to an increment threshold for humancontrast sensitivity, which is calculated based on a luminance in anarea of the image onto which the visible light for the interference isprojected in a superimposing manner.
 31. The system for interferingagainst image capturing of claim 26 characterized by radiating thevisible light for the interference from the front of the screen, andinterfering against an illegal activity by using a reflected light off asurface of the screen.
 32. The system for interfering against imagecapturing of claim 26 characterized by radiating the visible light forthe interference from behind the screen, and interfering against theillegal activity by using a transmitted light that transmits through thescreen toward the view side.
 33. The system for interfering againstimage capturing of claim 26 characterized by radiating the visible lightfor the interference from behind the screen, and interfering against anillegal activity by using a passing light that passes through a passingpart in the screen and travels to the viewer side.
 34. The system forinterfering against image capturing of claim 26 characterized in thatthe visible light for the interference, which is radiated onto thescreen, is a beam of light that is reflected off a means of reflection.35. The system for interfering against image capturing of claim 26characterized by including a plurality of units of the visible lightradiation means, and a control means for the visible light radiationmeans radiates the visible light for the interference at a plurality oflocations on the screen in prescribed combinations, in such a way that atwo dimensional optical image pattern is simultaneously recorded, whenan image on the screen is illegally image captured.
 36. The system forinterfering against image capturing of claim 26 characterized by furtherincluding, when an image being presented is projected onto the screenusing a film based means of projection, a light shuttering perioddetection means for detecting a period during which a projection lightis shuttered by a frame forwarding shutter; a calculation means fordetermining a luminance of a white color light for the interferencebased on an average luminance between a previous frame and an ensuingframe in a target image pixel; and a control means for projecting thewhite color light for the interference on to the target image pixelduring the period in which the projection light is shuttered.
 37. Thesystem for interfering against image capturing of claim 26 characterizedby further comprising, when an image being presented is projected ontothe screen by a film based means of projection, a light shutteringperiod detection means for detecting a time period in which a projectionlight is shuttered by a frame forwarding shutter; a calculation meansfor determining a luminance and a chromaticity of the visible light forthe interference, based on an average luminance and an averagechromaticity between a previous frame and an ensuing frame in a targetimage pixel; and a control means for projecting the visible light forthe interference onto the target image pixel during a period in whichthe projection light is shuttered.
 38. The system for interferingagainst image capturing of claim 26 characterized in that the system forinterfering against image capturing further includes a radiationdirection drive means for driving the visible light radiation means andchanging its directions of radiation; a storage means for storingradiation direction information for the visible light radiation meansthat correspond with screen sizes; and a radiation direction controlmeans for automatically adjusting the direction of radiation of thevisible light for the interference, which is an output from the visiblelight radiation means, by reading out appropriate radiation directioninformation from the storage means, when an instruction for changing thescreen size is detected, and providing a read-out radiation directioninformation to the radiation direction drive means.
 39. A system forinterfering against image capturing characterized by including a visiblelight radiation means for radiating a visible light for theinterference, that satisfies the conditions below, and radiates thevisible light for the interference from a screen side toward the viewerside so as to interfere against an image on the screen from beingillegally image captured: (1) Because of the human visioncharacteristics, an optical image for the visible light for theinterference is difficult to distinguish from an image being projectedonto the screen. (2) Because of the characteristics of a means of imagecapturing, an optical image for the visible light for the interferenceis recorded and distinguishable from the image on the screen, when theimage on the screen is illegally image captured.
 40. The system forinterfering against image capturing of claim 39 characterized in thatthe visible light radiation means outputs a composite light consistingof a plurality of single colored lights, that have differentchromaticities, as the visible light for the interference.
 41. Thesystem for interfering against image capturing of claim 39 characterizedby further including a control means for variably controlling achromaticity and a luminance of the visible light for the interferencein response to the image being presented that is projected onto thescreen.
 42. The system for interfering against image capturing of claim39 characterized by further including a control means for controlling achromaticity of the visible light for the interference in such a way asto match a chromaticity of the image being presented, which is projectedonto an identical area of an optical image for the visible light for theinterference.
 43. The system for interfering against image capturing ofclaim 39 characterized by further including a control means forcontrolling a luminance of the visible light for the interference tolower than or substantially equal to the increment threshold for humancontrast sensitivity, which is calculated based on a luminance in anarea of the image onto which the visible light for the interference isprojected in a superimposing manner.
 44. The system for interferingagainst image capturing of claim 39 characterized in that the visiblelight for the interference passes through a space outside of the screenand is directly radiated toward the viewer side.
 45. The system forinterfering against image capturing of claim 39 characterized in thatthe visible light for the interference is radiated by the visible lightradiation means at a back side of the screen, and a transmitted lightthat transmits through the screen and travels toward the viewer sideinterferes against an illegal activity.
 46. The system for interferingagainst image capturing of claim 39 characterized in that the visiblelight for the interference is radiated by the visible light radiationmeans at a back side of the screen, and a passing light, that passesthrough a passing part in the screen and travels toward the viewer side,interferes against an illegal activity.
 47. The system for interferingagainst image capturing of claim 39 characterized in that the visiblelight for the interference is radiated by the visible light radiationmeans embedded in the screen, and the visible light for theinterference, that is emitted from a surface of the screen toward theviewer side, interferes against an illegal activity.
 48. The system forinterfering against image capturing of claim 39 characterized byincluding a plurality of units of the visible light radiation means, andcharacterized in that a control means for the visible light radiationmeans controls so as that the visible lights for the interference from aplurality of locations on the screen are outputted in prescribedcombinations, thereby a two dimensional optical image pattern isrecorded simultaneously, when the image on the screen is illegally imagecaptured.
 49. The system for interfering against image capturing ofclaim 39 characterized by further including, when the image beingpresented is projected onto the screen by a film based means ofprojection, a light shuttering period detection means for detecting atime period during which a projected light is shuttered by a frameforwarding shutter; a calculation means for determining a luminance of awhite color light for the interference based on an average luminancebetween a previous frame and an ensuing frame at a target pixel; and acontrol means for radiating the white color light for the interferencefrom the target pixel during a time period in which the projection lightis shuttered.
 50. The system for interfering against image capturing ofclaim 39 characterized by further including, when the image beingpresented is projected onto the screen by a film based means ofprojection, a light shuttering period detection means for detecting atime period during which a projection light is shuttered by a frameforwarding shutter; a calculation means for determining a luminance anda chromaticity of the visible light for the interference based on anaverage luminance and an average chromaticity between a previous frameand an ensuing frame in a target pixel; and a control means forradiating the visible light for the interference from the target pixelduring a time period in which the projection light is shuttered.